Advertisers are expressing frustration with the inconsistency and apparent gender bias of Facebook’s censorship policy, pointing out that images of men without shirts are deemed acceptable by the social media giant, but picture’s of women’s bare shoulders are considered too sexually suggestive. Author Krista Venero, who uses the pen name K.L. Montgomery, told The New York Times that an ad for one of her books was rejected because it showed the upper portion of a woman’s bare back. When she disputed Facebook’s decision, she was told by a representative that the ad was blocked because it implied nudity and had “a sexual undertone.”

“I do have one [advertisement] that has a man’s chest, and I’ve never had any problems with it,” explained a frustrated Venero. “But a woman’s shoulder — we have a problem.”

In the wake of scrutiny, Facebook retreated and acknowledged that its censors had been wrong to block Venero’s ad. But Venero’s struggles with the companies opaque censorship process, which is conducted through a combination of automation and human review, are hardly a one-off affair. Speaking with The New York Times, book blogger April Ray said she was “stung” after a photo of her reading in a dark room in a black T-shirt was flagged as adult content by censors. By the time Facebook re-approved her ad, she said, the event that the image was meant to promote had already concluded.

According to Jillian York, the director for international freedom of expression at the Electronic Frontier Foundation, the censoring of women’s bodies can have sinister cultural consequences.

“Facebook’s policies have the effect of sexualizing women’s bodies in a way that is not necessary and very unhealthy for society,” said York.

Other advertisers told the Times about bizarre explanations and retractions they’d received from Facebook’s largely-male censorship staff, as well as telling of inconsistencies in the policy that governs how much skin men are allowed to show compared to what women are allowed to show.

This is a disgrace. Where is the UK foreign office in all of this? Aras Amiri now joins another British-Iranian, Nazanin Zaghari-Ratcliffe, in notorious Evin prison on bogus charges. @foreignofficehttps://t.co/DJX0knhdot